Как число преобразовать в строку? Python

a = '12345' # string
b = str(12345) # string
c = ''.join(map(str, range(1, 6))) # 12345

print('a: {}\nb: {}\nc: {}\n'.format(a, b, c))
print('"a" is', type(a)) # "a" is
print('"b" is', type(b)) # "b" is
print('"c" is', type(c)) # "c" is